Rock-drill



(No Model.)

J. J.- MARTIN & P. CUNNINGHAM.

' ROCK DRILL.

N9. 437,609. Patented Sept. 30, 1890.

- WITNESSES. V INVENT'OH: 9a 44% A TTOHNE YS UNITED STATES PATENTOFFICE.

JOHN J. MARTIN AND PATRICK CUNNINGHAM, OF PINOS ALTOS, TERRITORY OF NEWMEXICO.

ROCK-DRILL,

SPECIFICATION forming part of Letters Patent No. 437,609, datedSeptember 30, 1890.

Application filed February 5; 1890| Serial N! 339,334. (No model.)

that will work rapidly, that will be durable,

and that will be especially adapted to hard rocks.

To this end our invention consists in a drill having a rounded serratedend forming two downwardly-projecting lips, and having twooppositely-curved cutting-edges between said lips, as hereinafter fullydescribed and claimed.

Reference is to be had to the accompanying drawings, forming a part ofthis specification,

- in which similar letters of reference indicate corresponding parts inall the figures.

Figure 1 is an inverted side elevation of the drill embodying ourinvention, showing the serration in the end of the drill and thecutting-edges of the same; Fig. 2, an inverted side elevation, the viewbeing taken at right angles to Fig. 1; Fig. 3, an end View showing thefaces of the drill and the cutting-edges thereon.

The drillA is provided with a serrated end, thus forming two lips 13,which are curved slightly outward from the drill-shaft, and which arerounded off at the ends, as shown in Fig. 2, so that they will present around edge to the rock. The lips B are convexed on the inner face andmeet in the center of the drill, and each lip is provided upon itsconvex face with an inwardly-curved convex cutting-edge a, which extendsfrom the edge of the lip nearly to the center of the drill.

The cutting-edgesaof the lips B are curved in opposite directions, sothat there will be a cutting-edge near each side of the drill. The edgesor are made slightly convex, and the faces of the lips B are beveledupon each side of the cutting-edges, so that the particles of rockbroken by the drill Will be forced away from said cutting-edges, leavingthem constantly free to cut. The bevel from the inner end of thecutting-edges should be very sharp, as shown in the drawings, so thatthe drill will be sure to clear itself.

The drill is operated in the usual manner, being driven into the rockand turned slightly after each blow of the hammer upon it. Theprojecting ends of the lips B will first pierce the rock and then thecutting-edgesawill out toward the center. The shape of the drill willenable it tobe turned very easily in the drill-hole as the rounded endswill not stick, and the rounded lips B and cutting-edges a will out veryrapidly into the rock. It will be noticed that the edges a are of suchshape that they will not be easily dulled, and consequently the drill isvery durable.

Having thus described our invention, what we claim asnew, and desire tosecure by Letters Patent, is-

As a new article of manufacture, a rockdrill provided with a serratedend forming lips having convex inner faces and rounded ends, andprovided on their convex faces with inwardly and oppositely curvedconvex cutting-edges, extending from the edges of the lips to oppositesides of a line passing through the center of the drill, as set forth.

JOHN J. MARTIN. PATRICK CUNNINGHAM.

Witnesses:

Gno. W. NORTON, A. D. PIERCE.

